Fiber optic position and shape sensing is known in the art. One example implementation of such technology employs a fiber optic cable installed along a robot appendage to provide the shape and position along the length of the cable and thereby the instantaneous shape of the appendage and spatial coordinates of various points along the appendage.
A prior art example optical fiber 100 has a cladding 102 and a core 104, as illustrated in FIG. 1. The refractive index of the cladding 102 is significantly less than the refractive index of the core 104.
An example optical fiber 106 for fiber optic position and shape sensing has a cladding 108 and three cores 110, as illustrated in FIG. 2. Other example optical fibers for position and shape sensing may have different numbers of cores, the number of cores selected by the engineer according to design requirements and constraints.
FIG. 3 provides a side view of a segment of one of the cores 110 of optical fiber 106. In this implementation of fiber optic position and shape sensing, fiber Bragg gratings 112 are spaced along the core 110 and separated by tethers 114. The fiber Bragg gratings 112 are designed to reflect particular wavelengths of light and to transmit the rest, whereas the tethers 114 transmit all wavelengths.
Interrogation of the fiber Bragg gratings 112 for strain information using known technology provides their spatial coordinates, and the spatial coordinates in turn provide the shape of the optical fiber 106. Non-limiting examples of the technology referenced herein are presented in U.S. Pat. No. 8,116,601 and U.S. Patent Application No. 2006/0013523, both of which are incorporated by reference in their entirety. Using such technology, the spatial coordinates may be determined for a gripper at the end of the robot appendage discussed above, and likewise the shape of the appendage itself may be determined.
However, the full potential of fiber optic position and shape sensing has yet to be fully exploited.